This application claims priority to Japanese application no. JP H11-337769, filed Nov. 29, 1999, the disclosure of which is hereby incorporated by reference in its entirety.
1. Field of the Invention
The present invention is a passenger restraining protective system for restraining a passenger with a seat belt retracting apparatus that retracts and draws out seat belt webbing. More particularly, the invention is a seat belt retracting apparatus for controlling the belt tension within a predetermined belt tension when the possibility of collision is predicted or when a collision is determined.
2. Description of the Related Art
Passenger restraining protective systems having a seat belt retracting apparatus for retracting a webbing generally protect vehicle passengers in an emergency by preventing the passengers from moving away from the seat and restraining them. Such an emergency is a collision where the vehicle undergoes a large deceleration.
Japanese Unexamined Patent Publication No. 6-286581 proposes such a vehicle shoulder belt apparatus. Upon prediction of the possibility of a collision with an obstacle, a first pretensioner comprising a retractable buckle is operated to restrain the passenger under a prescribed belt tension. To ensure sufficient protection, upon detection of a collision, a second pretensioner based on a gunpowder or a spring is operated to ensure restraint and protection of the passenger under a higher tension than achieved only upon operation of the first pretensioner. The first pretensioner operates when a collision predicting sensor predicts the collision, and then, when a 3-sensor or the like detects a large vehicle deceleration, and hence occurrence of the collision, the second pretensioner operates.
More specifically, determining whether to operate the second pretensioner is carried out always after determining whether the first pretensioner should be operated. In other words, operation of the second pretensioner always depends upon the operation of the first pretensioner. As a result, for example, when a car suddenly rushes out from the side in front of a car mounting a frontward collision predicting sensor, the collision predicting sensor cannot detect the rushing car in time, and it may be difficult for the sensor to output an operating signal of the second pretensioner before a collision or upon a collision, thus making it impossible to certainly cause the second pretensioner to operate when the collision cannot be avoided.
The first pretensioner brings over the buckle by retracting a wire with a motor. When the first pretensioner with the motor is provided on the buckle side, a problem occurs. Installation of the motor-based first pretensioner is difficult because the space available on the buckle side is very limited, while the installation of the motor may require a relatively large space.
The second pretensioner using gunpowder or a spring is provided on the retractor side. For installation of the second pretensioner on the retractor side, it is necessary to operate a clamp mechanism of the second pretensioner prior to operating the first pretensioner, and in addition, to lock drawout of the webbing retracted onto the retractor. This leads to more complicated control of various operations of the first and second pretensioners, to the necessity of providing a locking mechanism which locks drawout of the webbing upon operation of the first pretensioner, and to a troublesome operational control of the locking mechanism.
In the case of a slight collision, when the car is driven again after operation of the second pretensioner, it is difficult to control operation of the retractor and the slack of the webbing cannot be eliminated, making it difficult to restrain and hold the passenger.
The present invention was developed in view of the circumstances as described above and has as an object to provide a passenger restraining protective system which permits operating a second pretensioner upon determining the occurrence of a collision separately from operating the first pretensioner upon determination the possibility of a collision.
Another object of the invention is to provide a passenger restraining protective system which not only better facilitates installation of the first and second pretensioners, but also permits easier operational control thereof. another object of the invention is to provide a passenger restraining protective system which eliminates the necessity to provide a locking mechanism locking drawout of the webbing upon operation of the first pretensioner on the seat belt retracting apparatus.
To solve the aforementioned problems, the invention provides a passenger restraining protective system having a seat belt retracting apparatus retracting a webbing restraining a passenger, comprising a first pretensioner which operates when possibility of collision is determined to set the first belt tension higher than that of normal driving; a second pretensioner which operates when a collision is determined to have occurred to set the second belt tension higher than said first set tension; and a controller which, when a collision is determined to have occurred, causes the second pretensioner preferentially to operate, irrespective of the operation of the first pretensioner. The first pretensioner is provided in the seat belt retracting apparatus. A buckle pretensioner can be used as the second pretensioner.
Even after the second pretensioner stops operating, when the first pretensioner operates, the first pretensioner continues operating until the possibility of collision is resolved.
In the passenger restraining protective system of the invention, when a collision is determined, the second pretensioner is preferentially operated by the controller, irrespective of the operation of the first pretensioner, to set a second set tension higher than the first set tension that would result from the first pretensioner. As a result, even in case of a collision which cannot be detected by a conventional sensor for predicting a collision as described above, the passenger is restrained and protected by a strong restraining force. Particularly, when the first pretensioner is provided in the seat belt retracting apparatus, the necessity to control the operation of the second pretensioner during operation of the first pretensioner is eliminated. Further, it is not required any longer to lock the seat belt taken up on the retractor from withdrawal since such withdrawal is prevented.
In the present invention, the first pretensioner requiring a relatively large space for installation can be provided in the seat belt apparatus and the second pretensioner requiring a relatively small installation space can be provided on the buckle side. This makes it easier to install the pretensioner on the buckle side where only a small space is available.
Further, operation of the first pretensioner can be continued even after operation of the second pretensioner, until and unless the possibility of a collision is resolved. When a is driven after a slight collision, the slack of the webbing can therefore be removed without fail, thus permitting restraint of the passenger.